This invention relates to improvements in liquid chromatography apparatus, and more particularly to a high-sensitivity liquid chromatography apparatus including a detector using light for analysis.
A high-sensitivity liquid chromatography apparatus includes an absorption detector, a fluorescence detector or the like using light as means for monitoring a sample separated into components in a column. Prior art liquid chromatography apparatus including such a detector using light for analysis are broadly classified into a type in which a lamp with line spectrum is employed to analyze a specific substance with high sensitivity and a universal type in which a lamp with continuum spectrum is employed so that wavelengths used for measurement can be freely selected.
Further, from the viewpoint of the principle of measurement, liquid chromatography detection using light is generally classified into two methods, that is, an absorption method and a fluorescence method.
The prior art liquid chromatography apparatus based on the absorption method is further classified into a type employing a deuterium lamp of high stability as the light source producing the continuum spectrum and a type employing a mercury lamp as the light source producing the line spectrum. When these two types are compared with each other, the sensitivity of the former type is lower than the latter type due to the weak radiance of light emitted from the deuterium lamp although the former type is suitable for universal use. While, in the case of the latter type, the wavelengths that can be used for measurement are limited to, for example, 254 nm, 297 nm, 313 nm, 365 nm, 405 nm, 436 nm, 546 nm and 579 nm at which bright lines of mercury appear although the sensitivity of the latter type is higher than the former type.
On the other hand, the prior art liquid chromatography apparatus based on the fluorescence method employs a xenon short-arc lamp emitting light of strong radiance. However, the apparatus based on the fluorescence method is defective among others in that the lamp has a short service life, and an expensive power unit is required for energizing the lamp because the lamp consumes large power and a high voltage must be applied in the starting stage.
The prior art detectors have their individual defects as pointed out above, and a novel detector free from these prior art defects is now demanded.